Iron Fireman stoker rehab update

Today I had the chance to dig into the Iron Fireman stoker I picked up from Greg (LsFarm) a few months ago along with an EFM 350 boiler top. That thread is here: http://nepacrossroads.com/about13071.html

I started out wiring a new cord to the motor as the original piece of wiring that was left was really crunchy. I wanted to test the "volumeter" and damper setup, check the coal feed, and change the gearbox oil. I got the motor running and everything seemed to be OK, but the draft damper seemed to be rusty and stiff. I sprayed some PB Blaster on the shaft pivots and it started to loosen up with some crunching noises. Finally, it got REALLY loose and I thought that's not good. While testing it, I also noticed very little airflow through the tuyeres, and that was after I removed the cleanout plug and vacuumed out the retort real well.

I decided that I had to pull apart the air tube/damper/volumeter setup and see what was going on. Amazingly, they used brass 4-40 nuts with the steel screws, so I only had 2 or 3 that I had to chisel off the head. It took a little wrangling but it came apart with not too much difficulty. I wasn't quite prepared for what I found, tho....

It was plugged solid with several decades of mouse nests, acorns, etc. Unfortunately, it rotted out the damper flap and corroded the rest of the works pretty badly. I pulled out some pretty big chunks of flat rusty "something" that I thought were sheet metal pieces, but I believe I've got everything accounted for and it was just layers of dirt, rust, and mouse pee.

The damper flap is shot, but it pivots on a brass shaft, so I just need to make a new flap and drill out the screws that hold it on and replace it. The rod that actuates the damper from the "volumeter" diaphragm is also brass and just needs to be cleaned up. They used a really simple clevis/cotter pin setup to connect the rod to the damper. Amazingly, the diaphragm inside is still flexible and in good shape! Here's what it is supposed to look like:


It's a really clever setup where the main adjustment just controls the amount of air that is sent to the diaphragm based on airflow - it is self regulating so as to maintain constant airflow to the fire. The air damper can be set and locked manually in case something goes wrong with the automatic system. Looking forward to see how well it actually works.

I also cleaned out the tuyere slots today and discovered that only the top slots have direct access to the airbox. The lower and middle slots have a "wall" that would look like a "J" in a section view behind them that allows air flow down and through the slots, but keeps the fines inside the burn area. It's a clever design touch where the air has to go up, over, and then down and out:

As if that wasn't enough, I decided that the motor sounded like it had bad bearings and had to come off. There are 4 bolts that hold the blower wheel to the pulley/hub piece. Once those are removed, the motor can be removed and the blower wheel stays in the shroud, and the pulley/hub removed with a puller. Indeed, the motor bearings (sleeve bushings) were shot - the pulley side bushing had a good .010 or .015 slop around the shaft. So, the motor came apart to see what might be able to be done with it. It all looked to be in excellent condition except the bushings - windings, centrifugal switch (contacts were caked up a little tho), temperature cutout (it's a sealed motor), and rotor look great. The shaft that rides in the pulley end bushing is a bit worn (.001 or .002 undersize) but I think it will be OK. It looks like the motor didn't receive very good lubrication back in the day. But they don't build motors like this anymore, so I'm going to drop the rotor and two end bells at a local motor repair shop to see what can be done with them. I'm sure it will cost less than a new motor because it's a 1/6hp capacitor start - smallest commonly available today is 1/4hp, and small capacitor start motors aren't very common (or cheap).

The only part of the job I actually completed without finding something wrong was the gearbox oil change. The 60+ year old stuff came out, looking pretty dark like molasses, but no water and no chunks. I refilled it with Mobil 1 SHC 634 synthetic 140wt which is safe for bronze and brass gears unlike a GL-5 automotive gear lube.

I was pretty disappointed to find the extent of damage today, but at least it's pretty easily repaired. Fortunately, the important things are in great shape (tuyeres, auger, gearbox, and major sheetmetal), so once these few small items are taken care of, it will be ready for another 60 years.

Chris

Looks like you may be smoking some of that Southern ILLaNOID coal soon

always fun fixing something that has been in storage forever
reminds me of restoring my efm af150 stoker........the burn pot was packed full of acorns and nests and a few dead mice

My Iron Fireman stoker was full of mouse nests too, when Ifirst fired it up, nest material, stored food [corn and dog food] came out of the air slots and fines cleanout. I had to take mine partially apart to clean it.

I did not open up the main air duct though, I know it's clean after more than a season of use, but I'm currious about setting the flapper.. It's been awhile since I've burnt in my IF stoker,, I hope the mice haven't moved back in..

Greg L

Here is a bit more on how the draft control system operates.

The main air control does not adjust draft directly. All it does is change the angular relationship between the flap and the rubber "stopper". This is done by moving the pointer on the scale and fixing it with the wing nut. This entire assembly then rotates about the pivot point as the airflow varies (the scale and the pointer move together). Less airflow opens the rubber stopper, more airflow closes the stopper.



The rubber stopper is what sends air to the diaphragm in the "volumeter" thru the red plastic pipe. This in turn raises the rod which opens the main air damper. Therefore, as the airflow is decreased due to draft changes, ash buildup, or different coal, the stoker detects this and opens the airflow and vice versa. When the stoker stops, the main damper will close most of the way and "bank" the fire.


The air damper can be controlled manually by removing the wing nut from the primary adjustment and using it to fix the damper in the required position. The pointer is fixed and the pie shaped part moves with the damper shaft.

It is an interesting setup, but I wonder how well it works and is it any better than a simple intake shutter or manual damper? Guess we'll find out!

Those little bastards get into everything! They've cost me more money in air filters than I care to remember.

Decon takes care of the barn & the 4 cats got the house covered.

And now for a few pictures of the motor dissection. If I can get new bushings installed for a reasonable cost, I'll keep using it. The shaft does have some wear on the pulley end bushing journal, but I think it can be used as-is. These bushings have oil holes for the wicking, and also internal oil grooves, and I want to replace them with the same type, not a generic "oilite" bushing. I'll probably replace the starting capacitor, also It seems to work fine, but capacitors don't generally age well unless they are the metal encased, paper-in-oil type filled with yummy PCBs.

The motor windings look like they are burnt, but that's just the tar-like compound that they used to pot the windings into the housing. It is interesting to see the start windings (the fine gauge dark wiring) look almost to have a cloth type insulation - not the usual enamel. But everything passes the sniff-test, it just smells like the inside of a 60 year old motor.....Mmmm!